Factors influencing the biosynthesis of 1-deoxynojirimycin in Morus alba L.

1-deoxynojirimycin (DNJ), a piperidine alkaloid enriched in mulberry, exhibits strong competitive inhibition against the alpha-glucosidase. To maximally use mulberry and to understand the mechanism of DNJ formation, we studied factors influencing DNJ biosynthesis in Morus alba. The results showed that the aqueous HCl immersion was a relative high efficiency method. We first revealed the relationship between DNJ content and factors including geographic locations, soil properties, meteorological factors and harvest time. They are: mulberry shoots taken from the top part of the branches had the highest content of DNJ, followed by roots, young leaves and mature leaves; mulberry growing in areas with higher latitude had higher content of DNJ; alkaline and low total nitrogen content in soil was advantageous to the biosynthesis of DNJ; the active peak periods of DNJ biosynthesis in a day appeared at 06:00 to 10:00 a.m. and 18:00 p.m.